chr17-70175475-G-A

Variant names:

• chr17-70175475-G-A
• rs199473654
• NM_000891.3:c.436G>A

Variant summary

Our verdict is Pathogenic. The variant received 11 ACMG points: 11P and 0B. PM1 PM2 PP2 PP3_Strong PP5_Moderate

The NM_000891.3(KCNJ2):​c.436G>A​(p.Gly146Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 13/22 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G146A) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: KCNJ2 NM_000891.3 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2 O:1
• Conservation: PhyloP100: 10.0
• Publications: 7 publications found

Genes affected

KCNJ2 (HGNC:6263): (potassium inwardly rectifying channel subfamily J member 2) Potassium channels are present in most mammalian cells, where they participate in a wide range of physiologic responses. The protein encoded by this gene is an integral membrane protein and inward-rectifier type potassium channel. The encoded protein, which has a greater tendency to allow potassium to flow into a cell rather than out of a cell, probably participates in establishing action potential waveform and excitability of neuronal and muscle tissues. Mutations in this gene have been associated with Andersen syndrome, which is characterized by periodic paralysis, cardiac arrhythmias, and dysmorphic features. [provided by RefSeq, Jul 2008]

KCNJ2 Gene-Disease associations (from GenCC):

• Andersen-Tawil syndrome

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Orphanet, G2P, Labcorp Genetics (formerly Invitae)
• short QT syndrome type 3

  Inheritance: AD Classification: STRONG, MODERATE Submitted by: G2P, Labcorp Genetics (formerly Invitae)
• short QT syndrome

  Inheritance: AD Classification: MODERATE, SUPPORTIVE Submitted by: ClinGen, Orphanet
• familial atrial fibrillation

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• catecholaminergic polymorphic ventricular tachycardia

  Inheritance: AD Classification: LIMITED, NO_KNOWN Submitted by: ClinGen, Genomics England PanelApp
• long QT syndrome

  Inheritance: AD Classification: LIMITED Submitted by: ClinGen

ACMG classification

Our verdict: Pathogenic. The variant received 11 ACMG points.

• PM1: In a hotspot region, there are 7 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 6 uncertain in NM_000891.3
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the KCNJ2 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 51 curated pathogenic missense variants (we use a threshold of 10). The gene has 2 curated benign missense variants. Gene score misZ: 2.7459 (below the threshold of 3.09). Trascript score misZ: 3.9347 (above the threshold of 3.09). GenCC associations: The gene is linked to short QT syndrome type 3, short QT syndrome, Andersen-Tawil syndrome, familial atrial fibrillation, catecholaminergic polymorphic ventricular tachycardia, long QT syndrome.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.995
• PP5: Variant 17-70175475-G-A is Pathogenic according to our data. Variant chr17-70175475-G-A is described in ClinVar as Pathogenic. ClinVar VariationId is 67576.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNJ2	NM_000891.3	c.436G>A	p.Gly146Ser	missense_variant	Exon 2 of 2	ENST00000243457.4	NP_000882.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNJ2	ENST00000243457.4	c.436G>A	p.Gly146Ser	missense_variant	Exon 2 of 2	1	NM_000891.3	ENSP00000243457.2
KCNJ2	ENST00000535240.1	c.436G>A	p.Gly146Ser	missense_variant	Exon 2 of 2	1		ENSP00000441848.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Andersen Tawil syndrome;C1865018:Short QT syndrome type 3 Pathogenic:1

Dec 30, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glycine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 146 of the KCNJ2 protein (p.Gly146Ser). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with Andersen-Tawil syndrome (PMID: 17221872). In at least one individual the variant was observed to be de novo. ClinVar contains an entry for this variant (Variation ID: 67576). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt KCNJ2 protein function. Experimental studies have shown that this missense change affects KCNJ2 function (PMID: 17221872). This variant disrupts the p.Gly146 amino acid residue in KCNJ2. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 19931173). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic.

Andersen Tawil syndrome Pathogenic:1

Sep 12, 2024

3billion

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The variant is not observed in the gnomAD v4.0.0 dataset. Predicted Consequence/Location: Missense variant. Missense changes are a common disease-causing mechanism. Functional studies provide moderate evidence of the variant having a damaging effect on the gene or gene product (PMID: 17221872). In silico tool predictions suggest damaging effect of the variant on gene or gene product [REVEL: 0.96 (>=0.6, sensitivity 0.68 and specificity 0.92); 3Cnet: 0.99 (>=0.6, sensitivity 0.72 and precision 0.9)]. The same nucleotide change resulting in the same amino acid change has been previously reported to be associated with KCNJ2-related disorder (ClinVar ID: VCV000067576 / PMID: 17221872).The variant has been previously reported as assumed (i.e. paternity and maternity not confirmed) de novo in at least one similarly affected unrelated individual (PMID: 17221872). Different missense changes at the same codon (p.Gly146Ala, p.Gly146Arg, p.Gly146Asp, p.Gly146Val) have been reported to be associated with KCNJ2-related disorder (PMID: 12796536, 19931173, 24861851, 35460302). Therefore, this variant is classified as Likely pathogenic according to the recommendation of ACMG/AMP guideline.

Congenital long QT syndrome Other:1

Cardiovascular Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

This variant has been reported in the following publications (PMID:17221872).

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.59
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.99	D;D
Eigen	Pathogenic	0.90
Eigen_PC	Pathogenic	0.80
LIST_S2	Benign	0.0	.;D
M_CAP	Pathogenic	0.71	D
MetaRNN	Pathogenic	1.0	D;D
MetaSVM	Pathogenic	0.89	D
MutationAssessor	Pathogenic	4.3	H;H
PhyloP100		10
PrimateAI	Pathogenic	0.85	D
PROVEAN	Pathogenic	-5.5	D;D
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0	D;D
Vest4		0.98
ClinPred		1.0	D
GERP RS		4.9
Varity_R		0.93
gMVP		1.0
Mutation Taster		=13/87	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs199473654; hg19: chr17-68171616;